This type of ground contact load control apparatus is shown in Japanese Patent Application Laid-Open (koka,) No. H11-91329, for example. In the ground contact load control apparatus shown in that publication, a reaction force which is produced through operation of moving a sprung mass up and down by use of an active cylinder provided for each of the wheels is caused to act on the ground contact surface to thereby control the ground contact load.
In the ground contact load control apparatus shown in the above-described publication, the ground contact load of each wheel is changed by separately controlling the active cylinder provided for each wheel. Therefore, when the ground contact load of each wheel is changed, there is not only the concern of an accompanying change in the attitude of the vehicle body, but there is also the possibility of vertical vibrations being generated.